The present invention relates to a daisy wheel for a printer which includes a typewriter having a plurality of petals with a character head on the end of each petal. Hereinafter reference will be made to a typewriter although the invention also relates to any printing device.
Many presently existing typewriters utilize a print element known as a daisy wheel which has a plurality of evenly spaced petals about the circumference thereof with a character to be printed on a character head at the end of each of the petals as needed. Also, some typewriters have a print element known as a "thimble" because it is so shaped and which also has evenly spaced petals about the circumference thereof. Hereinafter, the term "daisy wheel" is also intended to include print elements such as "thimbles". These daisy wheels all have a common construction in that the petals are evenly spaced and each occupies one of the petal positions about the circumference of the daisy wheel. Normally there are 96 such positions, although in some cases there have been 100, in other cases 88 and, more recently, one daisy wheel had 400 characters thereon. The use of such a daisy wheel having equally spaced petals about the circumference thereof creates considerable difficulty when attempting to provide a print element with an alphabet such as Arabic, Farsi, Hebrew, Urdu, and the like because, in some cases, the characters are so irregularly shaped and variable in width that to type certain of these characters they have to be broken into segments and successive impressions are required which join the segments together when printed so as to form the proper character. Obviously such a procedure requires extremely accurate positioning of the successive character segments so that, when joined together, they appear as one. Further, difficulties are created in the stepping of the print wheel so that the petal is in the proper location to cause the printed segments to be joined.
Further, some characters require a dot or dots to be associated with them. Where the dot or dots are on the same character head with their associated characters as in the prior art, a large number of character heads are required to provide all such characters. Applicant avoids this problem by placing the dot or dots on a separate character head thus reducing the number of character heads required. This provides additional petal space which can be used in the present invention for wider character heads because less petals are required.
Thus, in summary, when letters such as Arabic letters are to be printed by prior art printers, some of them are so wide that the continuous portion is broken into segments with one segment being on the end of one petal and another successive segment being on the end of another petal. This requires more than one impression to form the continuous portion of a character and the portions of the character must meet perfectly so that the entire continuous character appears normal. Any slight imperfection in the positioning of either the print element or the carriage assembly results in the printing of an imperfect character because the two segments would not be joined properly. Further, by the use of a dot or dots on a separate character head, the number of petals required to include all characters is significantly reduced over the prior art thus allowing the extra petal spaces provided to be used for wider characters.